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1. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 09 Issue: 06 | Jun 2022 www.irjet.net p-ISSN: 2395-0072
© 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 633
Development of Battery Management System for Maximizing Battery
Performance in AVL Cruise/MATLAB/Simulink
Mayuraj Ekatpure1, Rohan Sevlikar2, Saurabh Kamble3
1,2,3 BE Mechanical Engineering, Savitribai Phule Pune University, Maharashtra, India
Prof. Arpita Ekatpure, Dept. of Mechanical Engineering, Savitribai Phule Pune University, Maharashtra, India
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Abstract -: In recent times the electrification of automotive
powertrains is a major area of research and a lot of work has
been carried out to improve its performance in comparison
with its internal combustion counterparts. Among allongoing
research work, Battery Management System is one of the
major areas, which is used to improve the transient
performance and life of an electrochemical battery mainly a
Li-ion one. In this paper, we have focused our attention on the
crucial parts of the Battery Management System which is, Cell
balancing, the State of charge of the battery, etc. Based on the
literature review, various control strategies are studied and a
new optimal control strategy is defined to improvethebattery
performance according to application. The control strategy is
developed using MATLAB/SIMULINK. In this paper. we
developed an active and passive cell balancing model. For the
active cell balancing technique, we chose switched capacitor
technique. To have longer battery life, time required for the
cell balancing must be as low as possible for which many
control logics have been defined. So, various graphs are
compared, to find the effect of these cell balancing techniques
on the performance of the battery pack.
Key Words: AVL Cruise, BMS, Cell balancing, MATLAB,
SIMULINK, Passive, Active, Switched-Capacitor.
1. INTRODUCTION
Because BMS is the connector between the battery and the
car, it plays a critical role in enhancing battery performance
and optimizing vehicle operation in a safe and dependable
manner. Consequently, considering the rapid growth of EV
and HEV markets, there is an urgent need to develop a
comprehensive and mature BMS.
In this study, first, we simulated the vehicle standard data in
order to understand the AVL cruise then, the similar vehicle
is transformed into an electric vehicle. Further analysis of
developed model will be examined using AVL cruise and
performance will be evaluated in real time environment.
Further to optimise the battery performance, we are using
different cell balancing techniques to increase the battery
pack performance in MATLAB-SIMULINK. Today
Rechargeable batteries are most widely used for many
applications such as electrical appliances, smartphone,
industry etc. They are consideredasbestoptionfor electrical
and hybrid vehicles due to their advantage of having High
energy density, low maintenance, more charge cycles, Low
self-discharge rate compared to other batteries available in
the market. But the due to low cell voltage of this cell we
need a high-power battery pack to use them in case of
electric vehicle. But considering the disadvantage of
temperature rise in the cell we cannot use single battery cell
in a bulk rather we have to use multiple cells connected in
series to get higher output voltage [1].
Major factor that is affecting the uniformity of the cells is the
non-uniform temperature distribution. Due to multiple
charging and discharging cycles the net cell voltage will drift
down and will cause a decrease in the net capacityofthecell.
For example, consider multiplecellsconnectedinseries, now
cell with the higher internal impedance will show higher
voltage than that of other cells connected in series. Till time
other cells reach the maximum capacity first cell be
overcharged and this will leadtoincreaseinthetemperature
and the gaseous pressure within the cell causing its failure.
Hence to increase the overall battery capacity and to avoid
the battery failure battery management system has to be
adopted. In this case we mainly focus on the cell balancing
techniques to avoid overcharging of the cells for which we
have two main methods: Passive and active balancing. The
passive balancing technique uses shunt resistors to bypass
the additional voltage in the form ofheatduring thecharging
and discharging cycle [2,3].Incaseofactivebalancingcharge
from higher voltage cell is transferred to the lower voltage
cell using active elements like capacitors and inductors and
fly back DC-DC converters [4,5,6,7]. There are several
embodiments of capacitor cell balancing methods in the
literature [8,9,10,11].
Therefore, in this study, we emphasize on using MATLAB-
SIMULINK software for control technique used for cell
balancing to reduce the balancing time for each cell in
battery pack to attain the responses (charge-discharge,
variation of SOC of each cell, etc). Further, we can also study
to implement or do a co-simulation of proposedtechnique in
Simulink with the vehicle model in AVL Cruise.

2. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 09 Issue: 06 | Jun 2022 www.irjet.net p-ISSN: 2395-0072
© 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 634
2. BATTERY PACK DESIGN:
2.1 DESIGNING OF MOTOR AND BATTERY:
The vehicle's propulsion unit generatestheforce required to
propel the vehicle forward. This force assists the vehicle in
overcoming resistive factors such as gravity, air resistance,
and tire resistance. To find the longitudinal performance
characteristics of a car we need to consider first the forces
acting on it while traveling in a straight line. The major
external forces acting on a two-axle vehicle are –
1. Aerodynamic resistance Ra.
2. Rolling resistance Rr of the front and rear tires Rrf and
Rrr.
3. Drawbar load RD.
4. Grade resistance RG, (W sin θ).
5. Tractive effort of the front and rear tires Ff and Fr (For a
rear-wheel-drive vehicle, Ff = 0, whereas for a front-wheel
vehicle, Fr = 0).
Fig -1 Free body diagram of the vehicle
Total aerodynamic drag acting on the vehicle is given by:
Where:
V = Car Velocity
ρ = Air Density
Cd = Drag Coefficient Af = Frontal Area
Rolling Resistance acting on vehicle due to tyre is
composed primarily of
1. Resistance from tire deformation
2. Tire penetration and surface compression
3. Tire slippage and air circulation around wheel
4. Wide range of factors affect total rolling resistance
Total rolling resistance acting on the vehicle due to tyre is:
Total gradient resistance acting while climbing the slope
Is
A combination of the l above forces will give us the total
force acting on the vehicle at that constant speed.
Total Vehicular Resistance at Constant Velocity:
Power rating required by the motor can be given as:
Motor Power Required = Ftr * V (Vehicle speed in m/s)
There are many battery cells available but considering the
specific energy of lithium-ion batteries, most of the
automobiles use lithium-ion cells to develop a battery pack.
Based on the required output capacity we can design the
battery pack. For an electric vehicle very high voltage rating
is required and the battery pack required is thereby of
higher capacity.
This high-power output can be obtained by connecting cells
in series and parallel. The power rating of the battery
depends on the total terminal voltage of the battery. This is
given by the below relation:
P = U * I
Where; U = Voltage
I = Current.
(NOTE- Higher current across the circuit generates higher
thermal heat so one has to consider optimum value for
voltage as well for the current rating. Also, an appropriate
cooling system has to be considered for heat dissipation
across the battery pack.)

3. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 09 Issue: 06 | Jun 2022 www.irjet.net p-ISSN: 2395-0072
© 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 635
Motor has to develop a torque that is required by the
vehicle based on the resistive forces acting on it. Power
output of the motor will be determined by considering the
losses. Below isthe total power developed by the motor.
Net power input provided by the motor is given by below
relation which will account for the losses. This power will be
further transferred to the drivetrain.
Where,
The total energy required by the motor can be
determined by integrating the power that the motorhas
developed.
Based on calculation T = 27.35 Nm at 393.206 RPM Using
motor catalogue motor selected is PM BLDC
2000W,48V,4200RPM
3. Battery Capacity
The range of electric vehicles basedonthebatterycapacityis
given by the relation:
Table 1 - Important parameters
Table 2 - Calculations
Table 3 - Calculations
Based on the above calculation it is found that the
capacity of battery required is around 8 kWh on the plain
road when the vehicle is running at a speedon50kmph. And
that on the road with 12- a degree gradient battery capacity
required is equivalent to 100 kWh. But in the actual road
driving scenario we don’t drive at constant speed rather it
depends on thedriving condition due to which theoretical
calculated capacity is to high. Hence to determine the
VEHICLE PARAMETERS
Aerodynamic Drag Coefficient 0.38
Air Density 1.23
Front Area 2.1
Mass of Vehicle 2300
Rolling Resistance Coefficient 0.01
Wheel Radius 0.34
Accessory Load 600
Vehicle Speed 50kmph
Gear reduction Ratio 3.55
Power(W)
Torque at
Wheel (Nm)
Motor RPM
Required
4505.49288 17.23523379 686.4820798
10015.59941 38.31349909 686.4820798
15524.02921 59.38535025 686.4820798
21029.10605 80.44437509 686.4820798
26529.15475 101.4841653 686.4820798
32022.50162 122.4983185 686.4820798
37507.47505 143.4804401 686.4820798
42982.40594 164.4241451 686.4820798
48445.62827 185.3230604 686.4820798
53895.47957 206.1708265 686.4820798
59330.30146 226.9610992 686.4820798
64748.44011 247.6875522 686.4820798
70148.24677 268.3438783 686.4820798
Motor Torque
(Nm)
Accessory
Load(W)
Battery
Capacity
(kWh)
4.854995434 600 7.65823932
10.79253495 600 15.92339911
16.72826768 600 24.18604381
22.66038735 600 32.44365908
28.58708883 600 40.69373212
34.5065686 600 48.93375243
40.41702538 600 57.16121257
46.3166606 600 65.37360891
52.203679 600 73.5684424
58.07628914 600 81.74321936
63.932704 600 89.89545219
69.77114146 600 98.02266016
75.58982487 600 106.1223702
actual

4. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 09 Issue: 06 | Jun 2022 www.irjet.net p-ISSN: 2395-0072
© 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 636
performance we simulate the vehicle model in AVL Cruise
software or in MATLAB. We can consider the mean velocity
of the driving cycle and calculate the power and capacity
required using the above calculations.
Chart 1- Motor Torque Vs. Vehicle Speed Variation
Chart 2 - SOC Vs. Time Variation
Chart 3- Battery Power Vs. Vehicle Speed
Chart 2 shows all the points at which my motor is operating
at.From figure wecan tell that atspeedof25-35mphmotoris
operating a lot. Graph also helps to decide the size of the
motor based on the working point distribution. If points are
running out from the Torque line means we need to have
larger motor for that particular drive cycle.
Fig 2- Simulink Model

5. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 09 Issue: 06 | Jun 2022 www.irjet.net p-ISSN: 2395-0072
© 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 637
Fig 3 - Control logic flow chart for a passive system
In state flow diagram, operations are carried out based on
the current state of the system and based on the logic
provided system goes into the nextstate. Thisconceptcan be
easily understood from the flowchartgiveninfig. 15.System
will be continuously monitoring the state of charge and
voltage of each cell within the battery pack. When in the
difference between the maximum Voltage
and the minimum Voltage is greater than 2% its assumed
that cells are imbalanced and balancing protocol will be
executed ad system will go into balancing state. Now the
system will monitorVoltage of each cell and based on the
logic provided it will arrange the cell in ascending order on
their voltages. From the flow chart above let’s assume that
cell 1 has the lowest voltage (or say SOC) in this case other
two cells should be discharged unless and until their SOC is
equivalent to the third cell (approximate Error of 2%). For
this to happen system will ON the switch 2 and switch 3
which will connect cell 1 and cell3 to shunt resistor which is
connected in parallel to cell. The resistor will discharge the
cell by giving out charge in form of heat. Meanwhile system
will keep checking the SOC difference once the difference is
below 2% balancing sequence will stop and all the MOSFET
will on OFF state.
4. Result
Based on the results obtained it can be seen that time
required for the balancing is 6000 seconds. Oncethecellsare
being balanced based on the discharger logic battery will
start to drain and cycle repeats for given time span.
Fig 4 - SOC change during chargeanddischargecycleVsTime
5. CONCLUSION
It is very important for BMS to be well-maintained for
battery reliability and safety, proper state monitoring and
evaluation, and functional cell balancing and charge control.
Dueto these reasons, there is a needforBMSoptimization for
EVs to increase the reliability of BMS and optimize Ev’s
power performance. From this paper, we can conclude with
the following points-
 Active balancing was continuous whereas passive
balancing was not continuous and the time taken at
higher SOC is very high.
 Costing of passive balancing could be very high for
the larger battery pack and the cost does not justify
the balancing time required.
 By adopting different active balancing techniques
and different control logic wecan furtherreducethe
balancing time and hence increase the overall life
and performance of the battery pack.
In the future, we can implement or do a co-simulation of the
proposed technique in Simulink with the vehicle model in
AVL Cruise for validating the effect of techniques used in
BMS.

6. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 09 Issue: 06 | Jun 2022 www.irjet.net p-ISSN: 2395-0072
© 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 638
REFERENCES
[1] (Emadi, June 2088), "Power electronicsandmotordrives
in electric, hybrid electric, and plug-in hybrid electric
vehicles," IEEE Trans. Ind. Electron, vol. 55. pp. 2237- 2245,
June 2008.
[2] Stuart A. T., and Zhu W., “Fast Equalization for Large
Lithium-Ion Batteries”, IEEE Aerospace and Electronic
Systems Magazine, Vol. 24, pp. 27-31, 2009.
[3] Zhang X., Liu P., and Wang D., “The Design and
Implementation of Smart Battery Management System
Balance Technology”, J. Convergence Information
Technology, Vol. 6, No. 5, pp. 108-116, May 2011
[4] Cao J., Schofield N., and Emadi A., “Battery balancing
methods: A comprehensive review”,IEEEVehiclePowerand
Propulsion Conf., VPPC08, pp. 1-6, 2008.
[5] Daowd M., Omar N., Van Den Bossche P., and Van Mierlo
J., “Passive and active battery balancing comparison based
on MATLAB simulation”, IEEE VehiclePowerandPropulsion
Conf., VPPC 2011, pp. 1-7, 6-9 Sept. 2011
[6] Kutkut N. H., Wiegman H., Divan D. M. and Novotny D. W.,
“Design considerations for charge equalization of an electric
vehicle battery system”, IEEE Trans. Industry Applications,
35(1), Jan. 1999.
[7] Moore, S. and Schneider, P., “A Review of Cell
Equalization Methods for Lithium-Ion and Lithium Polymer
Battery Systems,” SAE Technical Paper2001-01-0959,2001,
doi:10.4271/2001-01-0959.
[8] West S., and Krein P. T., “Switched-Capacitor Systems for
Battery Equalization”, IEEE Modern Techniques and
Technology (MTT 2000). Proceedings of theVIInternational
Scientific and Practical Conference of Students, Post-
graduates and Young Scientists, pp. 5759, 2000.
[9] Pascual C., and Krein P. T., “Switched-Capacitor System
for Automatic Series Battery Equalization”, IEEE Applied
Power Electronics Conf. and Expo., pp. 848-854, 1997.
[10] Baughman A. C., and Ferdowsi M., “Double-Tiered
Switched- Capacitor Battery Charge Equalization
Technique”, IEEE Trans. Industrial Electronics, Vol. 55. pp.
2277-2285, 2008.
[11] Sang-Hyun P., Tae-Sung K., Jin-Sik P., Gun-woo M., and
Myung-Joong Y., “A New Battery Equalizer Based on Buck-
boost Topology,” IEEE 7th Int'l Conf. Power Electronics, pp.
962-965, 2007.